First-principles calculations of α-alumina (0001) surfaces energies with and without hydrogen

We used first-principles, mixed-basis (pseudo-atomic and plane-wave basis functions) pseudopotential calculations to study the energetics and structure of the alpha-alumina (0001) surface for three different terminations as well as two different hydrogen covered surfaces. The calculations show that over the range of chemical fields where a-alumina is stable, the stoichiometric (1-Al terminated) surface is the most stable with a surface energy of 2.13 J/m(2). The lowest values of the 2-Al-terminated and oxy gen terminated surface energies are 2.7 and 3.5 J/m(2), respectively. We find that hydrogen bonds weakly to the stoichiometric surface with a binding energy of 0.5 eV/bond and prefers to sit directly on top of the terminating Al atoms. Finally, we find that an oxygen terminated surface with one hydrogen atom per surface oxygen has a levier surface energy over the relevant range of chemical fields.